Mitsuru Kodera

Spin-Polarized AM05 Functional for 3d-Transition Metals

We performed the first-principle calculations for the 3d-transition metals (Fe, Co, Ni) with the different exchange–correlation functionals, LDA, PBE, PBEsol, and AM05. We found that the ground state of Fe with the AM05 is not the ferromagnetic bcc phase but the nonmagnetic hcp one unlike that with the PBE. The results of AM05 for the 3d-transiton metals are not so accurate as the PBE, but are very close to the those of the PBEsol.

Density functional scheme for calculating the ground-state pair density

Abstract We present an approximate scheme for calculating the pair density (PD) by means of the extended constrained-search theory. The single-particle equation of the auxiliary noninteracting system is derived on the basis of the variational principle with respect to the pair density. It is the modified Hartree–Fock (HF) equation that additionally contains the kinetic contribution of the exchange-correlation energy functional as the correlation term. The present scheme can provide a better total energy than that of the HF approximation.

Simultaneous equations for calculating the pair density.

We propose a practical scheme for calculating the pair density (PD) on the basis of the density functional theory. In order to avoid the N-representability problem of the PD, we implement the variational principle within the set of PDs that are constructed from the single Slater determinants (SSDs). For the kinetic energy functional, we utilize the approximate form that is developed by means of the electron-coordinate scaling laws. The variational principle results in the simultaneous equations for constituent orbitals of the SSD. It yields the best one within the SSD-representable PDs.

A Proposal for Calculating the Orbital-Dependent Exchange-Correlation Potential by Means of the Virial Theorem

We provide a density functional scheme for calculating the orbital-dependent exchange-correlation potential using the virial theorem as a sum rule. This is different from the optimized effective potential (OEP) method. To confirm the validity, atomic-structure calculations are performed for closed-shell atoms. The exchange energies are in good agreement with the previous values obtained by the OEP method, whereas the numerical speed has been considerably improved.